Flying internationally and domestically with a plant?

I'm flying with SAS from Stockholm to Newark, and I want to take a little plant with me I got in Sweden, I think it's a type of lilly. I've looked on the website and I can't find anything on regulations and rules. it's small enough to fit in my purse so that's what I'm planning on doing. Then from Newark I'm flying to Minneapolis with Frontier Airlines. So any help on how to do this and any papers I need to get would be helpful! Thank you so much!